Like Razorleaf, many PLM administrators use virtualization to power their test and development systems. When VM performance degrades, defragmenting virtual disks and virtual machines can help - but there are special steps to follow.

1. PLM Tip Defragmenting VMs

2. Why Fragmentation Slows Performance File writing, moving, and rewriting splits files over time (files go in the first available space) Seek time adds to overall retrieval time when reading from hard disks (seek increases when files are split) Compare: 10msec read 5msec read + 2msec seek + 3msec read + 2msec seek + 1msec read + 2msec seek + 1msec read (15msec)

3. How VM Fragmentation is Different VM Fragmentation Files fragmented across the virtual disk Virtual disk fragmented across multiple files Virtual disk files fragmented across physical disk versus Physical Fragmentation Files fragmented across the physical disk

4. Steps to Defragging VMs Defrag Guest OS (Defraggler on Guest) Defrag Virtual Disk (VMware Utility) Defrag Host OS (Defraggler on Host)

5. Defrag Guest OS Moves files into contiguous areas where possible, but may not move all guest files into a single virtual disk file

6. Defrag Virtual Disk Consolidates virtual files making up the disk, to the greatest extend possible

7. Defrag Host OS Moves virtual disk files into contiguous area

8. Useful Tools VM defrag (built-in with VMware) Defraggler Windows defrag Diskeeper